A few days ago, I recieved my AKG K701. I'm used to Grado GS1000, but after playing the AKG's for about 40 hours, the Grados were send back in their carton.
WOW ! The AKG K701 is just my kind of headphone. They just got the sound I've been searching for. The midrange is almost as my old Sennheiser Unipolar 2002 electrostatic headphones; neutral and detailed. Treble is clear, but not so harsh as with my Grados. Bass is tight, but at the same time neutral. If deep bass is present on the recording, it will be played. Otherwise not. My Sennheiser HD650 play very deep bass almost every time bass is present, but its not as natural as when presented from the AKG's. Soundstage is huge from the AKG's. Grado GS1000 also got nice soundstage, but not quite as good / wide as the K701.
One of the best things I discovered, when switching from Grado GS1000 to AKG K701, is female voices. They are much better with the AKG's. Powerfull yet detailed and "pleasant". Your ears will never get tired from listening to female voices from the AKG K701.
Just my experience with AKG K701, after 40 hours of "burn in". I was told that burn in can take 100 or even 300 hours ?! Well, I'll probably hear the difference. The sound changed a lot for the first 40 hours; it simply gets better and better.